Torque converters include a shell that typically are formed as a brazed or welded assembly of a front cover and an impeller shell. The torque converter shell experiences significant cyclic operating stress from centrifugal forces of the hydraulic fluid located therein and from operating automatic transmission fluid pressure to apply or release the torque converter clutch. The operating stress can cause the front cover or impeller shell to crack or fracture, which results in the hydraulic fluid leaking and failure of the torque converter. The thickness and geometry of the torque converter shell are designed to minimize operating stresses. The impeller shell includes vanes on an inner surface which in addition to their torque transfer function, also provide increased stiffness, improving deflection and durability against the operating stress. In contrast, the front cover typically lacks additional features that would provide durability against the operating stress other than formed steps. Accordingly, the front cover is the component of the torque converter shell that typically fails during operation. However, depending on the particular application, either part of the torque converter shell may fail.
Known solutions for increasing the durability of torque converter shells include increasing the thickness of the front cover and/or the impeller shell. However, increasing the thickness of these parts also increases the mass of the torque converter shell, which increases manufacturing costs as well as operating costs due to the increased weight and mass moment of inertia of the torque converter. Accordingly, it would be desirable to increase the durability of a torque converter shell without increasing the mass of the front cover or impeller shell.